<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width,initial-scale=1,user-scalable=no">
<title>Test REM</title>
<style>
	html{
		font-size: 40px;
	}
	body{
		font-size: 20px;
	}
	.use_em,.use_rem{
		font-size: 14px;
	}
	.use_em span{
		font-size: 1em;
	}
	.use_rem span{
		font-size: 1rem;
	}

	.img_em{
		width: 2em;
		height: 2em;
	}
	.img_rem{
		width: 2rem;
		height: 2rem;
	}

</style>
</head>
<body>

<div class="use_em">
	<span>font-size使用em</span>
</div>

<div class="use_rem">
	<span>font-size使用rem</span>
</div>

<p>图片使用em</p>
<img src="../images/face01.jpg" class="img_em">
<p>图片使用rem</p>
<img src="../images/face02.jpg" class="img_rem">

</body>
</html>